System.NullPointerException: Attempt to de-reference a null object

Can anyone help with this error?

    System.NullPointerException: Attempt to de-reference a null object

    Class.productdata.getMapOfContent: line 24, column 1

Here is the Apex Class. "Line 24" refers to "if(LoopContentData.TagCsv.contains(getTag())) {"

public class productdata {

    LIST<ContentVersion> allContentData= [select Available_To__c, IsLatest,ContentModifiedDate, Title, ReasonForChange, VersionNumber, RatingCount, Description, ContentDocumentId, TagCsv, ContentDocument.ParentId FROM ContentVersion WHERE IsLatest=TRUE];
    LIST<CONTENTWORKSPACE> WorkspaceObjects = [SELECT Name, ID FROM CONTENTWORKSPACE];
    MAP<string,LIST<ContentVersion>> MyMapOfContent = new MAP<string,LIST<ContentVersion>>();
    //string prod = [SELECT Name FROM Product2 WHERE Id = :ApexPages.currentPage().getParameters().get('id')].Name;
    string prod;
    product2 myProduct;

    public productdata(ApexPages.StandardController controller) {
        this.myProduct = (Product2)controller.getRecord();
    }

    public String getTag(){
        return prod = [SELECT Name FROM Product2 WHERE Id = :myProduct.ID].Name;
    }


    public MAP<string,LIST<ContentVersion>> getMapOfContent(){
        for(CONTENTWORKSPACE loopIds : WorkspaceObjects){
            LIST<ContentVersion> theContentVersionMapLoop = new LIST<contentversion>();         
            for(ContentVersion LoopContentData : allContentData){
                if(LoopContentData.ContentDocument.ParentId == loopIds.ID){
                    if(LoopContentData.TagCsv.contains(getTag())) {
                        theContentVersionMapLoop.add(LoopContentData);
                    }
                }
            }
            MyMapOfContent.put(loopIds.Name,theContentVersionMapLoop);
        }
        return MyMapOfContent;
    }

}

I know it has something to do with getTag method but I have no idea why. Thanks!